From: Xi Wang <xi.wang@gmail.com>
Date: Mon, 23 Apr 2012 08:06:41 +0000 (-0400)
Subject: drm/i915: fix integer overflow in i915_gem_execbuffer2()
X-Git-Tag: v3.3.5~53
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4a265435c87b19175c3906ff49ffe5bf4a4cc228;p=thirdparty%2Fkernel%2Fstable.git

drm/i915: fix integer overflow in i915_gem_execbuffer2()

commit ed8cd3b2cd61004cab85380c52b1817aca1ca49b upstream.

On 32-bit systems, a large args->buffer_count from userspace via ioctl
may overflow the allocation size, leading to out-of-bounds access.

This vulnerability was introduced in commit 8408c282 ("drm/i915:
First try a normal large kmalloc for the temporary exec buffers").

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 65e1f0043f9df..6911b591d9608 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1353,7 +1353,8 @@ i915_gem_execbuffer2(struct drm_device *dev, void *data,
 	struct drm_i915_gem_exec_object2 *exec2_list = NULL;
 	int ret;
 
-	if (args->buffer_count < 1) {
+	if (args->buffer_count < 1 ||
+	    args->buffer_count > UINT_MAX / sizeof(*exec2_list)) {
 		DRM_ERROR("execbuf2 with %d buffers\n", args->buffer_count);
 		return -EINVAL;
 	}